Some considerations that are of primary concern to building owners deal with reducing energy costs and conserving energy. For example, lighting directly accounts for about 40% of the electricity consumed in a typical building. Leaving lights on after hours or during long periods when they are not being used is a tremendous drain on energy and profits. Turning them off, on the other hand, is an instantaneous cost reduction. Reducing the amount of time that lamps burn each day can also substantially increase the amount of time between replacements, saving on labor, material and disposal costs. Controlling electrical loads such as lights-turning them off when not needed-conserves energy, saves money, and helps the environment. This is not only cost effective, but is often required by federal and state laws in new or renovated buildings.
One way to better manage energy consumption is to use remote-controlled circuit breakers. In general, a remote-controlled circuit breaker includes a remote-controlled actuator having a small electric motor, which responds to appropriate control signals sent from a remote location for automatically separating a pair of contacts of the circuit breaker. Therefore, the circuit breaker can switch the electrical power of an electrical circuit ON or OFF during certain time periods. The remote-controlled circuit breaker has many applications, such as controlling light systems in commercial buildings.
Some electrical applications require a multi-pole circuit breaker. When a multi-pole circuit breaker includes a remote-controlled actuator, each pole is typically remotely controlled in the same manner, i.e., the remote-controlled actuator controls all the poles in the same time. This means that all the poles will receive the same command and will operate identically. For example, if the circuit breaker has two poles, each pole controlling a different set of light fixtures, then both set of light fixtures will turn ON at the same time and will turn OFF at the same time, according to the remote-control command.
In one application, emergency lighting systems, such as exit signs and lights, are required by law in commercial buildings to provide minimum lighting for exiting a building when electrical power is interrupted. Generally, emergency lights run on battery power and remain illuminated for only a limited time, e.g., at least 90 minutes. The National Electrical Code (“NEC”) Article 700-12(e), which pertains to unit equipment used for emergency lighting, states in part that the “branch circuit feeding unit equipment shall be the same branch circuit as that serving the normal lighting in the area and connected ahead of any local switches.” The purpose of this article is to ensure that the emergency lights turn ON when the electrical power for the normal lighting is interrupted, e.g., power is lost, disconnected, or turned OFF.
The NEC requirement effectively prohibits the use of conventional remote-controlled circuit breakers in emergency illumination applications. A party that wants to use a multi-pole remote-controlled circuit breaker in connection with emergency lighting will encounter at least one of two problems. If the emergency lights are connected to one pole and the normal lights are connected to another pole or poles, then the emergency lights are not on the same branch circuit with the normal lights. This violates the NEC requirement. If the emergency lights and the normal lights are connected to the same pole, then the emergency lights will turn ON whenever the normal lights turn OFF. This is obviously an undesired effect when it is desired to regularly turn OFF the normal lights, during such times as when a commercial building is closed. In other words, there would be a false alarm (the emergency lights turn ON) every time the building closes.
Therefore, there is a need for a remote-controlled circuit breaker wherein all the poles receive the same electrical power, and a remote-controlled actuator controls at least one but less than all of the circuit breaker poles. For example, in a two-pole circuit breaker, both poles receive the same power, but one pole can be remotely controlled without affecting the other pole. Thus, if a first pole is coupled to emergency lights and a second pole is coupled to normal lights, the remote-controlled actuator can operate to turn the normal lights ON and OFF according to desired schedules while the emergency lights are unaffected by the remote-controlled actuator.